<?php
/**
 * @link http://www.tintsoft.com/
 * @copyright Copyright (c) 2013 TintSoft LLC
 * @license http://www.tintsoft.com/license/
 */
namespace Leaps\Caching;

/**
 * ApcCache提供APC缓存的应用程序组件。
 *
 * 使用这个应用程序组件,  [APC PHP extension](http://www.php.net/apc) 必须被加载。
 * 为了使APC CLI你应该添加 "apc.enable_cli = 1"到你的 php.ini.
 *
 * @author Tongle Xu <xutongle@gmail.com>
 * @since 4.0
 */
class ApcCache extends Cache
{
	/**
	 * @see \Leaps\Caching\Cache::exists()
	 */
	public function exists($key)
	{
		$key = $this->buildKey($key);
		return apc_exists($key);
	}

	/**
	 * 从缓存检索值与指定键。
	 * 这是在父类中声明方法的实现。
	 * @param string $key一个独特的键确定缓存值
	 * @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
	 */
	protected function getValue($key)
	{
		return apc_fetch($key);
	}

	/**
	 * Retrieves multiple values from cache with the specified keys.
	 * @param array $keys a list of keys identifying the cached values
	 * @return array a list of cached values indexed by the keys
	 */
	protected function getValues($keys)
	{
		return apc_fetch($keys);
	}

	/**
	 * Stores a value identified by a key in cache.
	 * This is the implementation of the method declared in the parent class.
	 *
	 * @param string $key the key identifying the value to be cached
	 * @param string $value the value to be cached
	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function setValue($key, $value, $expire)
	{
		return apc_store($key, $value, $expire);
	}

	/**
	 * Stores multiple key-value pairs in cache.
	 * @param array $data array where key corresponds to cache key while value
	 * @param integer $expire the number of seconds in which the cached values will expire. 0 means never expire.
	 * @return array array of failed keys
	 */
	protected function setValues($data, $expire)
	{
		return array_keys(apc_store($data, null, $expire));
	}

	/**
	 * Stores a value identified by a key into cache if the cache does not contain this key.
	 * This is the implementation of the method declared in the parent class.
	 * @param string $key the key identifying the value to be cached
	 * @param string $value the value to be cached
	 * @param integer $expire the number of seconds in which the cached value will expire. 0 means never expire.
	 * @return boolean true if the value is successfully stored into cache, false otherwise
	 */
	protected function addValue($key, $value, $expire)
	{
		return apc_add($key, $value, $expire);
	}

	/**
	 * Adds multiple key-value pairs to cache.
	 * @param array $data array where key corresponds to cache key while value is the value stored
	 * @param integer $expire the number of seconds in which the cached values will expire. 0 means never expire.
	 * @return array array of failed keys
	 */
	protected function addValues($data, $expire)
	{
		return array_keys(apc_add($data, null, $expire));
	}

	/**
	 * Deletes a value with the specified key from cache
	 * This is the implementation of the method declared in the parent class.
	 * @param string $key the key of the value to be deleted
	 * @return boolean if no error happens during deletion
	 */
	protected function deleteValue($key)
	{
		return apc_delete($key);
	}

	/**
	 * Deletes all values from cache.
	 * This is the implementation of the method declared in the parent class.
	 * @return boolean whether the flush operation was successful.
	 */
	protected function flushValues()
	{
		if (extension_loaded('apcu')) {
			return apc_clear_cache();
		} else {
			return apc_clear_cache('user');
		}
	}
}
